The present invention relates to a mobile radio terminal containing antennas and, in particular, to a mobile radio terminal containing two switchable antennas.
Conventionally, as an antenna for a small mobile radio terminal such as a mobile telephone, a self-contained antenna may be adopted. In this case, the self-contained antenna has a size which can hold a volume to some extent so as to keep communication performance. When a self-contained antenna is adopted, an antenna element may be disposed near the internal lower end of a body or casing of a mobile radio terminal. In this case, at some positions of the hand holding the body, the palm may cover the antenna element. As a result, the sensitivity of reception may decrease.
On the other hand, a mobile radio terminal having upper and lower bodies is provided and is known (such as Japanese Unexamined Patent Application Publication No. 11-177485, which will be called Document 1, hereinafter) in which these upper and lower bodies are connected through a hinge mechanism. Each of the upper and lower bodies contains an antenna element. Even when the sensitivity of reception of one antenna element decreases, the other antenna element is selected so that a decrease in sensitivity of reception of the mobile radio terminal can be prevented. Here, the two antenna elements in the mobile radio terminal are switched for a stand-by mode and a conversation mode. In other words, one antenna element is used only during a conversation while the other antenna element is used for a non-conversational, stand-by mode.
WO 02/0545332A1 (called Document 2, hereinafter) discloses a mobile radio termninal as described below. The mobile radio terminal has upper and lower bodies, and these upper and lower bodies are connected through a hinge mechanism. Each of the upper and lower bodies contains an antenna element. However, both of the two antenna elements are used as diversity antennas. Furthermore, one antenna element is disposed near the hinge mechanism in the lower body. Therefore, the lower body has a projection for accommodating the one antenna element at the upper part.
Yet, a mobile radio terminal disclosed in Document 1 and 2 includes two antenna elements separately contained in upper and lower bodies. One of the two antenna elements may be selected as required. Thus, in the hinge mechanism, an antenna connection line is required for one of the antenna elements.
A mobile radio terminal disclosed in Document 2 must have a special projection for containing an antenna element on the upper side of the lower body. Because of the existence of the projection, the length of the lower body is much larger than that of a general mobile radio terminal.